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C. E, SGREBNER. DYNAMO ELEGTMG MAGHINR No. 509,954. Patemmo. 5, 1893.

UNITED STATES -PATENT OFFICE,

- -CHARLES EL SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION partof l.'[qetlet' Patent, N0. 509,954, dated December 5,1893. I Applicatlon'led .Tune 1, 1889. SsrinlNo. 31.21918. (No model.)

l To all whom it may concern:

Be it known that I, CHARLnsE. SQRIBNER, acitizen of theUnited States, residing at Clicago, in the county of Cook and State oflllinois, have invented a certain new and useful .Improvement in Dynamo-Electric Machines,

(Case No. 188,) of which the following is a full. clear,-concise,and exact description, ref-I erence being had to the accompanying drawings, forming a part of this specification.

In the operation of a dynamo ,elect-ric ma` chine the coilsl are short circuited successively and during the time each is short circuited the polarity of its current changes; such a short circuiting occurs twicein the revolution of each coil or each distinct portion'of the armature. The coils intermediate of the shortcircuited coils at anygiven instant I have termed the currentproducing coils. I have discovered that in'nrder that objectionable sparking may be avoided at the brushesthat the currentbuilt upjineach coil-while it is short circuited should be of. the same direction and strength as that in the circuit-ofthe current producing coils'intdwhichitfis-intro; duced when the short circuit is re moved; thatis to say, while each coil is shortcircuited its current goes to ero and then is built upto a. certaineztent; by controlling the building up -ofthis current in such. manner. as to make the current built up equal toi-that in the circuit `of the current producingA coils iutowhich it is` l introduced objectionable-sparkin g isavoided.

I thus control theb'uildingupof the current in the short circuited coils by makin g'the field ol1 iorcev aecting such coils. of vthev proper strength to 'produce the desired result.

- In my application Serial blo-312,921 (Case No. 196) I have described and claimed the method of preventing sparking 'which consists in building up'currentin the short circuited coil while it is short circuited vequal in amount to the current in the current producing coils into thecircuit of whichl the-short circuited'coil is introduced. I

My invention 4herein consists essentially in providing a lieldvfor the short circnited coilsvwhich neld is energized byeld magnets having their windings in a circuit having a current vwhich is approximately constant.

My invention further consists in providing another,

a i'eld for the current producing coils which fieldl is energized'by the field magnets having their windings in a shunt circuit around thel translating devices, as for example, around the arc lights of an electric lighting system. The construction is such that the machine is self regulating without movement of any of the parts of the dynamo with lrelation to one.

In'the accompanying drawings-Figure I is a diagram illustrative of' an arc light circuit connected with a dynamo embodying my invention. Fig. 2 is an isometric view of the commutator,armature-and field magnet poles showing the relation of the poles to the short circuited coils.

Like parts are indicated by similar letters ofv reference throughout the dilerent figures. lteferringV now to Figui it. will bessen that the main circuit a including| the lamps may be traced through the coils h c d e of the field magnetsof the short circuited coils and t' hence through 'the pairs of brushes fg., The poles h i are thus magnet-ized by the coils b c d e included in the main circuit. In addition to these field magnets of the short ci'rcuited coils A I have provided the pair of magnets lo l providedwith the coils m n; these coils m 'n are included in a shunt circuit between points o p, points o 1o being connected with dilerent sides of the arc light circuit; these magnets lo l are in position to influence the current producing coils. That is to say, the magnets lol which have their coils included in the shunt between the points o p on dilerent sides of the lamps are so placed with reference to the brushes and the revolving armature as to produce a field, the lines of force of which are cut by the portions oli the armature which I have denominated'as tkloni'rent producing coils. Now it is evident thatasthe nu mber ot' lamps inlthe circuit is increasedjthe current remaining the same as required more current will be sent through vthe coils m fn,- in other words the increase of work vto be doneincreases the iield of the coils which produce the current to do the work, and'vice versa. The poles h l being north the poles 'i lc'should be south. Y

The poles h *larein .position to produce a .ield which is out by theshort circnitedfcoils rent in the circuit of the and the windings b ed 'c must be lfnoportioned` with reference to the main field magnets; in other words, the winding of these coils b c d e4 must be such that the circuit built up in the sliortcircuited coils will be equal to the curcurrent producing coils into which tlie'short circuited coils aie Introduced; therefore, this winding will be varied for different machines.`

I find that between fifty and sixty'thousand ampere turns No.16 wire upon poles which deteruiine the electro motive forceA of' the dynamo to a dynamo of one thousand to twelve hundred volts maximum capacity to be right to give the desired-regulation. The size of .the field should be s'o proportioned that this-number of ampere turns of Nol'1`6 wire, will have a resistance ,of from five to six hlundredohms. The main fields, may bevaried to give theproper current in the short circuited coil upon first building the dynamo, the number of ampere turns necessary depending upon the character of the iron used and the shape of the pole pieces of the main' field cores.

If the dynamo at one Athousand volts with 'the brushes clean 'gives a current higher than 1s desired a reduction in the number 'of am' pre 'turns upon themagnets whose poles h L' are placed over the short circuited coils can be made to bring the current to the desired strength.

I am aware that prior to my invention dy- .namos have been constructed in which more than two Afield magnet pole pieces vvere provided and in which the diei'ent -polepieces werevadjiistable in strength with relation to each other but in none of these .prior inventions vvas provision made for maintaining a.

practically constant'z'eld of force to be cut by the short circnited coils ot' the armature.

while the cther'portions of the field of force acting upon the curreit giving coils were variable. l

Having thus describediny invention, I claim as new and desire to secure by Letters Patent-fy l. In a dynamo electric machine, lthe combination with the armature, of field magnets adapted to produce a divided field, one por tion of the field being generated by a coil ineluded in the maincircuit and the other portion'being generated by a coil included in a shunt of theload, said fields being so disposed that the portion of the tieid generated by the main circuit energizes'the short circnited portion of the armature and the portion of the field generated by the shunt circuit energizes the rest of the armature.

2. In a dynamo electric machine, the conibination with an armature, portions of which are short. circuited during its revolutiomwith field magnets adapted to generate a field of force and energized by the current generated in said armature, one portion of said tield of force which is beingcut vby the short cir.- cuited portion of the armature being main'- tained at a practically constant strength, while the other portion of the field of force is varied automatically by the variation of the load.

- In Witness whereof I hereunto subscribe my naine this l7th day of May, A. D. 1889.`

ciiARLEs E. SCRIBNER.

Witnesses.

.ELLA EDLER, v GEORGE P. BARTON. 

